Valve which permits the circulation of work material during the stoppage of a cable sheathing press



A ril 28, 1959 VALVE WHICH PERMITS Tl lE CIRCULATION OF WORK MATERIALDURING Filed June 7, 1954 T A. LJUNGBERG 2,884,129

THE STOPPAGE OF A CABLE SHEATHING PRESS 2 Sheets-Sheet 1 April 8, 1959A. LJUNGBERG 2,884,129

VALVE WHICH PERMITS THE CIRCULATION OF WORK MATERIAL DURING THE.STOPPAGE OF ,A CABLE SHEATHING PRESS Filed June 7, 1954 2 Sheets-Sheet 2INVENTOR ATTORNEY United States Patent VALVE WHICH PERMITS THECIRCULATION OF WORK MATERIAL DURING THE STOPPAGE OF A CABLE SHEATHINGPRESS Ture A. Ljungberg, Stuvsta, Sweden, assignor to Allmanna SvenskaElektriska Aktiebola'get, Vasteras, Sweden, a corporation of SwedenApplication June 7, 1954, Serial No. 434,828 Claims priority,application Sweden June 9, 1953 2 Claims. (Cl. 207--4) fore enter thepress at a temperature which is considerably higher than the temperatureat which it is extruded. Therefore, a cooling flund has to be suppliedto the press, which fluid takes up the difference between the heatcontent :of the molten metal supplied and that of the extrudedsolidified metal. A press having a high output must, therefore, becooled considerably with respect to the temperature of the metal passingthrough the press, and if the metal becomes stationary for any reason orif the output decreases, the metal passing through the press becomescooled too much. If there are no particular arrangements for immediatelychanging the quantity of cooling fluid supplied, the molten metal in thepress can solidify .and give rise to great trouble in starting the pressagain. Stopping or slowing down of the extrusion process is often causedby external occurrences, for example the repair of worn insulation ofthe cable or exchange of the cable drum.

The present invention relates to means for enabling the extrusion speedto be altered without necessitating a change in the rate at whichcooling fluid is fed to the press. This is obtained by providing thepress with a controllable valve through which metal surplus to theextrusion requirement is discharged in the form of a tube or rod from azone in the press in which the metal is in a plastic condition. Themetal passing through the valve is preferably returned to a melting potfrom which the molten metal flows to the press. Due to the highpressures involved the walls of the press casing have considerablethickness. This makes it impossible for the control valve to be placedoutside the press, since if the control valve were placed outside thepress a considerable reduction of the pressure would then occur withinthe relatively long and narrow duct between the interior of the pressand the valve, which would give rise to greater friction resistance thanthe normal path of the metal through the press, and, therefore the valvewould become ineffective. The valve, therefore, comprises a seat mountedin the wall of the press, said seat preferably being positioned closerto the inner surface of said wall than to the external surface thereof.

On the accompanying drawings one embodiment of a press head for coveringcables with a metal mantle is shown comprising the melting pot for themetal and the supply pipe for the molten metal to the press head and thereturn pipe for the surplus metal from the pres head to the melting pot.Fig. 1 shows the press with the melting pot and the supply and returnpipes of the press head. Fig. 2 is a section through the press headtaken at right angles to the direction .of advance \of the cable throughthe press. Fig. 3 is a section through the press head taken along thecenter line of the cable along the line AA of Fig. 2. Fig. 4 shows thevalve according 2,884,129 Patented Apr. 2 8, 9

to 'the invention in enlarged scale. Fig. 5 shows in a still largerscale the valve as viewed in the direction of the arrow B in Fig. 2.Fig. 6 is a perspective view of the valve. Fig. 7 is .a view of thevalve from the other end of Fig. 5. The melting pot is designated by 11and the casing or press head by 12. Designated by 13 is the incomingportion of the cable and by 14 the outgoing portion of the metal-coveredcable, which is advanced through the press head in the direction of thearrow. Designated by 15 are heating elements arranged in the press head,the former also being provided within chan nels 16 around the foot ofthe press head. The heat is applied here, when the press is to bestarted. Designated by 17 (Fig. 2) are cooling water ducts located insaid foot, the purpose of which shall be described later on. The moltenmetal is suppiied through the pipe 18 into the casing containing thesupply screw 19, which is driven by a motor through a worm gear notshown on the drawings. The metal is subjected to a pressure by the screw19, and the molten metal is transformed into plastic state by thecooling fluid supplied through the cooling duct 17. The metal is thenpressed upwards into a duct 20 and around a mandrel 21 (Fig. 3) and outthrough an orifice 22, thereby forming the sheath .ofthe cable. Thepositions :of the mandrel 21 and the orifice 22 with respect to eachother, and hence the thickness of the sheath, are controlled by means ofthreaded sleeves 23 and 24. When the press is adjusted for normaloperation, molten metal is fed around the screw 19'1at the exact ratewhich is required in order to sheath the cable at that speed at whichthe latter is being advanced through the press. If now the speed ofadvance of the cable is reduced or if the cable is even stopped, so thatthe consumption of the molten metal for sheathing the cable decreases oris interrupted while the quantity of cooling water is the same, themetal within the press will soon solidify with the result that it willbe very diflicult to heat the press for starting it again. To preventthe metal from solidifying within the press head, the valve generallyindicated by 25 is inserted. It consists as shown in an enlarged scalein Fig. 5 viewed in the direction of the arrow B in Fig. 2 of a conicalplug or mandrel 26 having three or more wings 27, which engage the wallof a conical inner portion of a passage extending through the casingwall at a point downstreamward of the screw and in the zone of thecooling ducts where the metal has become plastic. 29 is a member havingan internal conical channel slidably mounted in the passage and having avalve seat engageable with the pointed end 28' of plug 26 which extendsbeyond the wings 27. A hollow screw or threaded member 30 is threadedlymounted in the passage to engage member 29. Member 30 has an internaltapered channel and is provided with a toothed gear wheel 31 for beingoperated remotely by means not shown :on the drawings. Fig. 4 shows theValve in closed condition. When the toothed wheel 31 is rotated in thedirection for opening the valve, the pressure exerted by the screw 19presses the valve seat member 29 in such a direction (to the left in thedrawing) that a gap is produced at 28 around the mandrel 26. By suitablyadjusting :said gap, a flowing off of the surplus metal is obtained atreduced speed of advance [of the cable, so that the risk for the metalto solidify in the press head at reduced speed of advance of the cableis eliminated. The surplus metal flows through the screw threaded means30 in the form of a tube the thickness of which depends on the magnitudeof the gap. The surplus metal may be led back to the melting pot 11 by apipe 32 (Fig. 1).

In operation, the gear wheel 31 (Fig. 4) is normally in such a positionthat the inner end of the screw 30 holds the valve seat of member 29 inclose engagement with the plug 26, so that there is no escape of surplusmetal, but when the extrusion process is slowed down or stopped, andescape of surplus metal is therefore desired, the gear 31 is turned soas to move the screw 30 outwardly, so that the annular seating surfaceat the right hand end (Fig. 4) of the valve seat member 29 is movedraway from plug 26 by the pressure of the metal against the inner faceof the valve seat, while the plug remains with its wings 27 in closeengagement with the tapered wall of the inner part of the passage. Thesurplus metal is then free to pass through the annular gap at 28 betweenthe parts 26 and 29, as the part 29 is moved outwardly (to the left,Fig. 4) by the pressure of the metal, and the surplus metal issuesthrough the part 29 and through the 'hollow screw 30, in the form of atube having a wall thickness determined by the setting of the gear 31and the consequent distance between the parts 26 and 29.

I claim as my invention:

1. A fluid-cooled metal press for the continuous extrusion of a metal toform a sheathing for longitudinally moving articles, in which the pressreceives the metal in a molten state and extrudes the metal in asolidified state after cooling 'in the press, said press comprising apress casing, :an extrusion screw in the casing, sheathing meanscomprising a core and a die located in the casing in advance of thescrew and through which the said moving articles are advanced, means forthe supply of molten sheathing metal to the screw, cooling fiuid ductsin said casing to bring the molten metal therein to a plastic condition,an escape passage extending through the wall of said casing and locateddownstreamward of said screw and in the zone of said cooling ducts,within the zone of the casing in which the metal becomes plastic, saidpassage serving for the escape of surplus plastic metal, and a valvearranged in said passage and controlling the passage of the plasticmetal through said passage so that the surplus metal can escape from thepress.

2. A metal press according to claim 1 in which the said valve comprisesa conical plug having an annular end surface and provided with outwardlytapered radial wings for the passage of the surplus metal therebetween,a conical bore in the said passage for receiving and retaining saidwings, a movable member in said passage having a valve seat adapted toengage the said annular end surface of said plug, said member beingprovided with an internal conical channel for the passage of the surplusmetal, a hollow :screw mounted within the said passage and engaging saidmember and provided with an internal tapered channel forming :acontinuation of the channel in said member, and a gear wheel foractuating said screw to adjust the distance between the said annular endsurface of the plug and the said member.

References Cited in the file of this patent UNITED STATES PATENTS1,193,859 Bary Aug. 8, 1916 2,025,666 Hanff Dec. 24, 1935 2,105,083 Kagiet al Jan. 11, 1938 2,161,570 Harris June 6, 1939 2,219,888 Duclos Oct.29, 1940 2,385,574 Hyprath Sept. 25, 1945 2,743,812 Ljungberg May 1,1956 FOREIGN PATENTS 271,378 Germany Mar. 11, 1914

